A robust control algorithm for self supported dynamic voltage restorer (DVR)

The protection to the sensitive loads from voltage sags, swells and harmonics can be achieved using the dynamic voltage restorer (DVR) in a cost effective manner. In this paper, a new control algorithm based on unit templates and instantaneous symmetrical component theory along with complex Fourier series is used for the generation of reference voltages for a dynamic voltage restorer (DVR). These voltages, when injected in series with a distribution feeder by a voltage source converter (VSC) with PWM control, can tightly regulate the voltage at the load terminals against any power quality problem in the source side. A capacitor supported DVR does not need any active power during steady state because the voltage injected is in quadrature with the feeder current. The control of the DVR is implemented through derived reference load terminal voltages. The proposed control strategy is validated through extensive simulation studies using MATLAB with its Simulink and Sim Power System (SPS) toolboxes. The DVR is found suitable to support its dc bus voltage through the proposed control under various power quality disturbances on source side.